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		<title>Document</title>
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	<body>
		<script>
			const s1 = new Set();
			console.log(s1.size);

			const s2 = new Set(['a', 'b']);
			console.log(s2.size);

			// 数组去重
			const s3 = new Set(['a', 'b', 'a', 'b']);
			console.log(s3.size);

			const arr = [...s3];
			console.log(arr);
		</script>
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